In 1931 some Ryoma-related documents, handed down in the Sakamoto family, were donated to the Kyoto National Museum by Sakamoto Yataro of Sapporo City, Hokkaido. These three scrolls comprise the main part of the donation. The first scroll has Ryoma’s letters pasted on it. Many of them are addressed to his sister Otome living at the family home in Tosa. The second has both writings by his ancestors and genealogical trees of the family. The third contains documents relating to Ryoma's company Kaientai. They are indispensable to the study of Sakamoto Ryoma, and are designated as Important National Properties in 1999.